Fuel pump



June 18, 1935. E. A. ROCKWELL FUEL PUMP Filed May 29, 1929 .l atente d June 18, 1935 FUEL PUMP Edward A. Rockwell, Chicago, Ill., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application May 29, 1929, Serial No. 366,842

6 Claims.

The purpose of this invention is to provide an improved apparatus of the nature of a pump for supplying fuel to an internal combustion engine, adapted to be operated bya cam on a shaft of the engine served, and for that purpose adapted to be mounted on-the body of the engine, as on the crank case, at an aperture in the engine casing through which an actuating element of the apparatus may extend into the engine casing cavity element. It consists in the elements and features shown and described as indicated-in the claims.

In the drawing: Figure 1 is a vertical section of a pumping apparatus embodying-this invention.

Figure 2 is a section at the line 2 -2 on Figure 1. Figure 3 is a section at the line 33 on Figure 1. The pumping apparatus illustrated in the draw ing is a pump of the type employing a flexible phragm being marginally clamped between mated flanges of two casing members, the diaphragm spanning recesses in the mated faces of the two members, of which the recess in one of the casing members forms a pumping chamber having fuel intake and discharge connections, valve-controlled, for fuel flow through the pumping chamber from a fuel source to the engine carbureter, the valves seating against reverse flow and the flexible diaphragm forming a moving wall of the pumping chamber and being flexed inwardly and outwardly with respect to the pumping chamber for intake and discharge of the fuel pumped.

As illustrated in the drawing, the pump is furnished with a fuel-receiving trapping chamber arranged to serve as a sediment trap, which chamber is connected so as to be interposed in the fuel supply linefrom the fuel source to the pump at a point antecedent to the pump intake valve, so that the fuel drawn by the pump passes through the fuel-receiving trap chamber before it reaches the intake valve, being delivered into the trap chamber at the upper part of the latter and drawn out also at the upper part, so that the trap chamber must be filled up to the level of the outflow port in order that the fuel may pass on to the pump.

This antecedent fuel trap chamber constitutes no part of the present invention, the pump as a whole being merely designed for being conveniently equipped with such an auxiliary device by the detail form of the casing member constituting the pumping chamber.

The, other casing member is arranged for mounting on the engine casing as above indifor co-operating with an engine-driven. actuating diaphragm as the pumping member, such diacated, and for accommodating the connections for operating'the pumping member,--the flexible diaphragm mentioned,-by a cam on the engine shaft, and particularly for affording guide bear-' ing for the diaphragm stem by which the diaphragm is vibrated for its pumping action.

Referring to thedrawing in detail:-The two casing members are designated'respectively A and B, the member, A, having the pumping chamber, a, is closed at one side by the flexible diaphragm,

C, which is marginally clamped between flanges,

Ill and 20, of the casing members, A and B, respectively.

The fuelinflow passage is seenat 30, and the discharge passage at 4ll, controlled respectively by inflow valve, 3|, and discharge valve, 4|. The casing member, A, has an overhanging extension, A in which the fuel inflow passage extends and the inflow controlling valve, 3|, is located, and to the under side of which the fuel trap and sediment chamber, D, is secured with the inflow passage discharging downwardly into it as seen at 32, and leading upwardly from it to the inflow valve as seen at 33.

The casing member, B, has a guide hearing as seen at 5| for the stem, 60, which is fitted closely in said bearing for preventing passage of liquid (as lubricant which may enter the cavity of the member, B, from the engine casing) into contact with the diaphragm, and said casing member, B, which is made open at the bottom to facilitate the introduction into' the cavity of the operating parts hereinafter described, is closed at said bottom opening by a plate, 56, suitably secured by bolts, with an intervening gasket, 56, for rendering the joint liquid-tight. v

The operating connections tothe stem, 60, of the pumping member comprise a lever, 52 fulcrumed on a pin, 53, set in the casing wall, said lever extending out through an opening,; 54, in the side of the casing member, B, which is arranged for mounting on the engine casing with said opening registering with the opening zdicated at H in the engine casing indicated at 10 he casing member, B, being formed with a flange seen at 55 having bolt holes, 56, adapting it to be secured to the engine body with the openings, 54 and H, registering as mentioned.

The other arm, 51, of the lever, 52, extends in the casing member, B, toward the diaphragm stem, 60, and has stopped upon its upper side a compression spring, 80, for which housing is formed in the casing member, B, as seen at 64 directly over the end of the lever arm, 51.

A second lever, 62, 'isfulcrumed on the fulcrum pin, 53, of the lever, 52, and extends from said fulcrum to a point substantially in line with the diaphragm stem, 60, at some distance from the end of said stem; and is connected by a link, 64, with the end of said diaphragm stem. The lever, 62, and the arm, 51;of the lever, 52, are arranged with the arm, 51, overhanging the lever, 62, in substantially the same vertical plane, and said two lever arms are connected by a stretched spring, 61, reacting for stressing their free ends toward each other. And said levers are provided with co-operating stop shoulders, 58 and 88, respectively, which encounter for stopping the approach of the lever members under-the stress of the spring, 61, at a. predetermined position of said lever members with respect to each other, which is the position at which the diaphragm, C, is at normal or substantially unfiexed position, and the lever, 52, is at the limit of its movement in the direction for following, with the end which is protruded into the engine casing, the actuating cam, I2, shown on the engine shaft,'13.

Upon considering the structure as above described, it may be understood that starting with the pumping and fuel line passages empty, the lever, 52, will be actuated by the cam, 12, in the active phase of the cam cycle, in the direction for causing the lever arm, 51, to compress the spring. 80, and stretch the spring, 67, or, through the medium of said spring operating as a link, to actuate the lever, 62, in the direction for thrusting the diaphr stem, through the medium of the link, 64, in the direction for giving the diaphragm, C, its feeding stroke; and the force of that stroke, it will be seen, will be limited to the force of the resilient reaction of the stretched spring, 61. And it will be seen that after the pump has been operating long enough to fill the carburetor float bowl, or other form of fuel chamber, to the limit for supplying the engine requirements, the feeding stroke of the diaphragm derived as described may be negligible, the entire movement of the lever arm, 51, being accommodated by the resilient yielding and stretching of the spring, 61, and the co-operating stop shoulders, 58 and 68, of the levers 52 and 62 respectively, being separated.

In the idle phase of the cam cycle it will be seen that the spring, 80, will cause the.cam-encountering end, 52 of the lever, 52, to follow the cam, and upon the shoulder, 58, encountering the shoulder, 68, the lever, 62, will be actuated by the resilient reaction of the spring, 80, in the direction for giving the diaphragm its intake stroke.

It will be seen, therefore, that the construction is adapted to give the diaphragm both its feeding stroke and its intake stroke yieldingly, with the force only of the reaction of the springs, 61 and 80 respectively; and that the lost motion for which provision is made between the co-operating shoulders of the two levers having their ful-- crum in common, serves the pin-pose of permitting the lever, 52, to follow the cam in the idle phase of the latter, avoiding lost motion between the cam and the lever, and preventing the knocking of the cam against the lever which would occur if the lost motion were permitted at that P int. Y

The arrangement of the parts for actuating the diaphragm impulser, C, is particularly advantageous. Inasmuch as the springs, 80 and 61, are not located in an upwardly directed pocket, the possibility of water accumulating and then freeznil in cold weather is avoided. This is an important feature inasmuch as the freezing of space in which the springs, 80 and 61 are located with the downwardly removable cover, 56, the parts, including the said springs, may be readily .assembled upwardly through the opening provided at the bottom and which is normally sealed by the said cover, 56. This arrangement is aided, furthermore, by providing the tension spring, 61, in the place of a compression spring for effecting the pumping stroke inasmuch as no enclosing pocket is needed for'the tension spring and as it is very important to avoid such pockets, especially for springs located in the lower part of the mechanism, as in the case of the pumping mechanism shown in Figure l of the drawing.

While I have described my invention above in detail, I wish it to be understood that many changes may be made therein without departing from the spirit-of the same.

I claim:-

1. A pumping apparatus for supplying fuel to the carbureter of an internal combustion engine comprising a casing having a pumping chamber and a. pumping member constituting a movable wall thereof, and having an operating stem reciprocably mounted in the casing; means for actuating said stem to give the pumping member its intake and discharge strokes, comprising two levers having a fulcrum in common carried by the pump v from the casing for positive actuation for rocking it in one direction about its fulcrum, a spring connecting the other arm of said first lever with the second lever, said second lever being operatively connected with the pumping member stem for actuating the pumping member in the direction of its feeding stroke by the movement of said second lever derived from the first lever through said spring, whereby said feeding stroke is communicated yieldingly; a second spring reacting between the casing and the first lever in the direction for causing the lever to follow the cam in the reverse direction of its positive actuation by the cam, the two levers having cooperating stops which encounter each other in said reverse movement; whereby the pumping member derives a yielding intake stroke from the reaction of said secondspring conditioned for such reaction by the positive actuation of the cam.

2. In the construction defined in claim 1, the

' mounted on an engine body and to be actuated by an engine cam,'in combination with a pumping chamber and a reciprocable pumping member therein, operating connections to the pumping member comprising two levers havinga common fulcrum and co-operating abutments stopping on each other for adapting each lever to actuate the other in one direction, a spring member reacting between said levers for stressing said abutments against each otheruthe first of said levers extending for positive actuation in one direction by an engine cam, the other lever being extended for connection with the pumping member, and a second spring reacting on the first lever in the direction for rocking said lever in the direction for actuating the second lever by the encounter of said co-operating abutments.

4. In combination, an impulser, a cam-actuated lever for actuating the same, a compression spring for causing the lever to follow the cam, a lever connected to the impulser having a lost motion connection with the first-mentioned lever, a tension spring reacting between the levers for providing a limited pressure feeding stroke, and a downwardly directed pocket in which the follower spring is carried.

5. In combination, an impulser, a cam-actu ated lever for actuating thesame, a compression spring for causing the lever to follow the cam, means for connecting said lever to the impulser comprising a tension spring for providing a limited pressure feeding stroke to the impulser and a second lever, embodying a lost motion connection between the first mentioned lever and the impulser, the tension spring being connected between the said levers.

6. In a pumping apparatus comprising a pump casing arranged to be mounted on an engine body for extension into the latter, a reciprocable pumping member in said pump casing, means in said pump casing for operating said pumping member comprising an actuating lever fulcrumed on a horizontal pivot and having associated with it a second lever similarly fulcrumed, the two levers having lever arms extending from their fulcrum in the same general direction, said arm of the first mentioned lever being above the arm of the last mentioned lever, a connection between the arm of the second lever and said pumping 

